A large number of seeds are observed, and their initial launch angles are recorded. The range of projection angles is found to be -51° to 75°, with a mean of 31°. Approximately 65% of the seeds are launched between 6° and 56°. (See W. J. Garrison et al., “Ballistic seed projection in two herbaceous species,” Amer. J. Bot., Sept. 2000, 87:9, 1257–64.) Which of these hypotheses is best supported by the data? Seeds are preferentially launched

(a) at angles that maximize the height they travel above the plant;

(b) at angles below the horizontal in order to drive the seeds into the ground with more force;

(c) at angles that maximize the horizontal distance the seeds travel from the plant;

(d) at angles that minimize the time the seeds spend exposed to the air.

The data shows that most seeds (65%) have launch angles between 6° and 56°, with a mean of 31°. And therefore, seeds are preferentially launched above the horizontal.

For maximum height, the projected angles should be close to 90°.

For option (a) to be true, most seeds must be launched at angles close to 90°, which is not the case. Hence option (a) is not the correct hypothesis.

Option (b) is false as most seeds are preferentially launched above the horizontal.

As most of the launch angles are between 6° and 56° with a mean of 31°, which is close to 45°, we can conclude that option (c) is the hypothesis that is best supported by the data.

Option (d) must also be not true; to minimize the time exposure, most of the seeds must be launched below horizontal close to -90°, which is not the case.