CSS grid introduced a new length unit, fr, to create flexible grid tracks. Referring to the code sample below, what will the widths of the three columns be?

.grid {
display: grid;
width: 500px;
grid-template-columns: 50px 1fr 2fr;
}

• The first column will have a width of 50px. The second column will be 50px wide and the third column will be 100px wide.
• The first column will have a width of 50px. The second column will be 150px wide and the third column will be 300px wide.
• The first column will have a width of 50px. The second column will be 300px wide and the third column will be 150px wide.
• The first column will have a width of 50px. The second column will be 500px wide and the third column will be 1000px wide.