This was not a situation where I was able to choose. I was given 50 seeds, there was no choosing
Did you get a chance to sample the herb the seeds came from? If so, then you should know. If not, then you could always ask the person the seeds came from.
The problem with someone asking if their plants are sativa or indica is that very few people actually grow either, as in pure sativa or pure indica. Once you get into crosses the differing amounts of each in a cross can be minimal and it can be almost total and it can be anywhere in between. Someone can look at a plant's leaves and say it appears to be predominantly sativa or indica but looks can be deceiving in regards to the high or stone or combination someone ends up with.
Basically no one in the world can look at pictures and say more than something appears to be more sativa or more indica and have any real chance of accuracy unless something is unquestionably predominant in one or the other.
An example would be the real true Romulan. Most people believe it is anything from a pure indica to predominantly indica but that is not the case. Canadian soldiers who returned from Korea during/after the Korean War brought home seeds and over the years they kept selecting the shorter bushier faster finishing phenotypes in their crops and breeding them and in time a tall lanky Korean sativa looked like an indica plant.
Some did cross indica with their Korean sativa but most gave up on that because it 'watered down' the high they liked and since through careful selective inbreeding they were able to make faster flowering plants that yielded more they did not see a reason to ruin a good thing by adding indica. Others also crossed other faster flowering sativa strains to shorten flowering time and retain a sativa high.
Later when the world got its hand on Romulan, the world in part meaning The Dutch Masters, and it ended up a mutt because more crossing was performed and indica was added.
Basically what I am saying is normally someone with mystery seeds will never be able to figure out more than a very vague general idea of what they MIGHT have. Between the number of original landrace strains and the 3000 or more known crosses that have been made and the countless numbers of mutts that people who do not know beans about breeding (no pun intended) have created either intentionally or accidentally the odds of guessing even half accurately what a strain is is just about up there with the odds of being struck by lighting and living on the same day that they win a mega-bucks lottery AND the Olsen twins bring Keira Knightly over to your place for a wild group romp in the sack involving a 55-gallon drum of lubricants and circus equipment.
Just out of curiosity, which would you prefer your plants to be, predominantly sativa or predominantly indica?