Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each of the numbered blanks from 34 to 38.

How can solar cells become (34)__________ enough to be commercially viable?

There are, of course, a huge range of ongoing efforts to address this problem. Among the most recent approaches to this problem comes from a team of physicists and engineers at MIT (35)_____ is using computer modeling and advanced chip-manufacturing techniques.

In December of 2008, researchers from the Research Laboratory of Electronics, and the departments of materials science and engineering and physics applied an antireflection coating to the front of ultrathin silicon films, plus a novel combination of multi-layered reflective coatings and a tightly spaced array of lines to the backs of the films. The result is photovoltaic cells with as much as 50 (36)______ more electrical output.

The carefully designed layers deposited on the back of the cell cause light to (37) _________ around longer inside the silicon layer, giving it more time to deposit its energy and produce an electric current.

The work has attracted interest from industry for (38) _______ranging from generating remote off-grid electricity to dedicated clean power.

(Source: https://engineering.mit.edu/)