A laser of wavelength 1524.8 nm is split using a beamsplitter into two similar power beams. Using mirrors, the beams are aligned to approximately co-propagate with the same polarisation and they cross each other with a small angle of 23.66 degrees. In the crossing region transverse to the beams there is an optical standing wave (optical lattice) - what is the distance between successive bright (or dark) intensity zones in μm? [Cross-polarised beams have no standing wave. 0.3% Accuracy needed.]

a) cold, dry

explanation:

continental polar masses are cold and dry air masses because the cold air cannot hold much moisture. as they move into warmer air, they can trigger precipitation.

i guess it’s a and b

the entire statement is true and correct.  

there's no diagram, nothing is illustrated, and no question is asked.

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.