1 The correct order is: e, a, f, b, d; c does not belong in the text.

The original text was:

Cotton is a very useful plant. Inside its round fruits, called bolls, are masses of white fibres. When the fruits ripen, they split and the fibres are blown away, spreading their seeds. But in the cotton fields, the bolls are picked before this can happen. Cotton grows best in warm, wet lands, including Asia, the southern United States, India, China, Egypt and Brazil.

(from Pocket Encyclopedia by A. Jack)

It is possible that the very last sentence could come first, although in this kind of text a very general statement (Cotton is a very useful plant) is more likely to precede a less general one (Cotton grows best …). It could also take second place in the text, but the repetition of cotton so soon after its first mention would seem redundant.

Linguistic clues that might have helped are:

Lexical field: the sentence about copper does not fit into the topic that is suggested by words like cotton, plant, fruit, fibres, fields, etc.

Repetition: Inside its round fruits … When the fruits ripen …

Use of referring devices:

- Pronouns: Cotton is a very useful plant. Inside its round fruits …

- Articles: … masses of white fibres … the fibres are blown away.

Use of linkers: But in the cotton fields …

These last three items – pronouns, definite article and linkers – are dependent on the text that precedes them. For this reason, none of the sentences that contain these items could satisfactorily serve as the opening sentence of the text.

This suggests that just as sentences have ‘sentence-forming’ devices, such as the agreement between a verb and its subject, texts have ‘text-forming’ devices that function to connect sentences with each other and to bind a text together into a complete whole, i.e. to make it ‘cohesive’.

2 There are both lexical and grammatical devices that serve to make the text cohesive.