7th grade advanced math. HELP ME?!?

The second and third options are correct. At midday, with t = 12 we have: D = 4sin(5.06) + 7 => 3.23924317....i.e. 3.2 metres The smallest value of D occurs for the minimum value of sin(0.48t - 0.7) i.e.

-1 Hence, minimum depth, D = 4(-1) + 7 => 3 metres Note: maximum occurs when sin(0.48t - 0.7) = 1 i.e. D = 4(1) + 7 => 11 metres....so, not 6th option. :).