solve these please?

42. What is the minimum data set that can be interpreted to yield two depths for a 1interface model? a. One shot into one end of a line of geophones. b. Two shots; one at each end of the line. c. One shot at each end of the line and one at it's centre. d. As many shots as it takes to get a refraction arrival at every geophone from both directions. 43. If the layer is dipping instead of flat, the ITM (Intercept Time Method) approach to interpretation is made a little more complicated because ... a. The critical angle changes if the interface is dipping. b. Dipping layers are "hidden" from refraction measurements. c. Depths under each geophone are required in this case. d. The second layer's velocity is not obtainable directly from the slope of refraction arrivals from one shot. 44. In a travel-time versus distance plot in seismic refraction, the slopes of the segments depend on the a. change in seismic velocity at the boundary b. seismic velocity in each layer c. seismic velocity and dip in each layer d. thickness of each layer 45. Two seismic refraction surveys have been done at two different sites, where the basic geological models are all believed to be single horizontal layer plus basement. The two time-offset plots have the same slope for direct arrival and refracted arrival, but differ in the intercept time. The intercept time at Site A is 20ms while at Site B is 35ms, so what can be concluded? a. Site A and Site B have exactly the same velocity model b. the surface layer in Site B is thicker than that in Site A c. the surface layer in Site A is thicker than that in Site B d. not enough information to give any conclusion 46. A common midpoint gather refers to a. seismic traces acquired from a single shot b. seismic traces that are acquired with a constant source receiver separation c. seismic traces that have been moveout corrected with respect to a central geometrical location. d. seismic traces that have a source and receiver symmetrically placed about a single location