does someone know what this is??

OBJ inside a box means the program interpreted whatever it was as the Unicode object replacement character (U65532). Either case means either the message was corrupted during transit, the file sent was in an image format that your phone/app can't handle, or there's a bug in your texting application.

Step-by-step explanation: Oh yeah Oompa ville is nice and sus

(a) the volume of the cone is 20/3 in3

hence, option a is correct.